This invention relates to distributed control of fluid flow paths in contexts in which the flow paths, the equipments coupled to the flow paths, or both may fail or be damaged, and more particularly relates to autonomously controlled pumps for such systems.
Seagoing vessels, regardless of whether they are intended for sport, commerce, or warfare, share in common the need to maintain their buoyancy and control in the face of potentially violent conditions including storms, grounding, and or hostile action. Maintaining control and buoyancy in the face of damage due to such violent conditions may require rapid amelioration of, or adaptation to, such damage. In a large ship, there may be many compartments, the entrances to which are separated by a sufficient distance from each other so that considerable time may be required for movement from one compartment to another. The existence of such compartments has in the past given rise to the need for an observer assigned to each compartment or set of compartments to monitor conditions. It might be thought that speaker tubes or telephones would be suitable for communicating between each of the various compartments and a control center or bridge, but there is a real possibility that damage to a compartment might also damage the communications equipment. Consequently, warships assign crew members to be messengers, whose duty is to carry information from the compartments to the control center or bridge in the event of a break in the communications. Damage to one compartment of a ship may require adjustments in many compartments, as for example when flooding of a compartment requires redistribution of the ship""s load or supplies to prevent excessive list. The adjustments may include operation of valves and switches within the compartments, as might be required, for example, to start pumps and open valves for the dumping overboard of bilge water, or for redistributing liquid fuel from tanks on one side of the ship to tanks on the other side. Because time is very important when attempting to cope with damage, warships have in the past stationed crews at various locations about the ship. These crews are charged with the duties of operating valves and switches as commanded or trained. In addition to such adjustments, additional crews must be provided to be on standby for firefighting, for damage repair, and for tending the injured. In the case of a warship, a portion of the crew must additionally be used for manning weapons and countermeasure. Since the tending of injured presupposes that some of the crew is not capable of performing its duties, the crew must, even when reduced in number by casualties, be large enough to be able to perform all of the tasks associated with tending a ship in distress. All of these considerations result in the manning of ships with crews large enough to provide xe2x80x9csurgexe2x80x9d capability for the handling of any emergency. A large battleship of WWII vintage had a crew in excess of 3000 men, and an aircraft carrier in the vicinity of 5000. Even modern missile destroyers require crews exceeding 300 persons.
The presence of such large crews inevitably has its effects on ship design. It will be clear that the housekeeping and support requirements tend to expand disproportionally as the crew grows larger. The ship itself must be large in order to hold the oversize crew, and must carry additional stores such as food, which makes it larger still. Food preparation areas must be larger with a large crew, and the additional food preparation personnel in turn require their own support staff and ship facilities. The cost of ships is adversely affected by the need for a crew of a size to provide surge capability, and the cost of operating such ships is directly increased by the supernumerary members of the crew. The operating cost is further increased by the need to maintain the supernumerary members. It is thus of great importance in ship design to take into account the staffing requirements of the ship, and to improve ship design in such a manner as to minimize the crew size.
A part of the invention is based, in part, on the realization that automation can fulfill some of the tasks now performed by supernumerary crew members.
A fluid flow system according to an aspect of the invention tends to cause a flow of fluid through at least one fluid affecting device, which may be a heat exchanger which transfers heat to or from a fluid such as water, or which performs some other act on the fluid. The fluid flow is induced by a set including a plurality of pumps, not all of which need be energized at a given time, and any one of which may fail. The system includes at least one fluid affecting device including a first port and a second port, which are connected by a path for the flow of the fluid between the first and second ports. The system also includes a controllable first pump which, when energized, produces pressurized fluid at a pressure port, and which, when not energized, at least tends to impede the flow into the pressure port of the first pump as a result of application of pressurized fluid to the pressure port of the first pump. In the case of positive-displacement pumps such as Roots-type pumps, the inherent design prevents retrograde fluid flow, and in the case of other pumps, such as centrifugal pumps, the pump may be associated with a check valve to prevent reverse flow. The system also includes a controllable second pump which, when energized, produces pressurized fluid at a pressure port, and which, when not energized, at least tends to impede the flow of fluid into the pressure port of the second pump as a result of application of pressurized fluid to the pressure port of the second pump. A sensing arrangement or means is coupled to the fluid affecting device for generating a sensed signal representing a control parameter associated with one of flow of the fluid and pressure of the fluid; this may be, for example, a flow meter coupled for sensing the flow of fluid through the fluid affecting device, or a pressure sensor coupled to the high-pressure side of the fluid affecting device, or even to the low-pressure side for some applications. A communication network interconnects the sensing means and the first and second pumps for providing a path for the flow of information relating to the sensed signal and of at least the state of the first and second pumps. An independent first software program is associated with the first pump. The first software program is preloaded with information about the second pump and the fluid affecting device, for receiving information including the sensed signal and the state of the second pump, and for transmitting over the communication network signals representing the state of the first pump. Similarly, an independent second software program is associated with the second pump. The second software program is preloaded with information about the first pump and the fluid affecting device, and is arranged for receiving information including the sensed signal and information including the state of the first pump, and for transmitting over the communication network signals representing the state of the second pump. Each of the first and second independent software programs controls its associated pumps so that (a) if the sensed parameter is such as to require fluid flow, a determination is made if the one of the first and second pumps with which it is not associated is pumping, and (b) for energizing the associated one of the first and second pumps if the sensed parameter is such as to require fluid flow and the one of the pumps with which it is not associated is not pumping.
In a particular embodiment of the invention, at least one of the independent programs is preloaded with information identifying one of the first and second pumps as a preferred or default pump.